Problems can arise after blood has been drawn by a syringe in transferring it by mail or other delivery means to a location for testing or centrifugation. Historically, blood has been removed from the syringe and transferred to a shipping container which is then sealed and shipped to a laboratory for further processing. Transferring a blood specimen from a syringe to another container increases the possibility of contamination which can influence the analysis, if one is to be made, or the blood can infect one who may come in contact with it.
To counteract these problems, multipurpose syringes have been developed which not only serve to draw blood, but the syringe itself becomes the storing and shipping container. One such syringe is sold under the trademark VACUTAINER by Becton Dickinson & Company of Rutherford, N.J. The VACUTAINER syringe includes an evacuated glass tube containing a pre-measured vacuum to provide a controlled, pre-specified draw. The glass tube is closed by a resealable plug in its forward end, the opposite end being permanently closed. The tube slides into the open end of a cylindrical holder which, at the other end, has a hollow needle or spike projecting inwardly and a venipuncture needle projecting outwardly from the plug. The venipuncture needle is inserted in a vein and the fixed vacuum tube slid into the holder until the rearwardly projecting spike pierces the plug and allows the vacuum within the glass tube to draw a measured quantity of blood from the vein. The glass tube is subsequently withdrawn from the holder whereupon the plug self-seals and the entire plugged tube may be shipped to a laboratory for further processing.
While this type of syringe is in common use, it is somewhat restricted because it will only draw a pre-specified amount of blood due to the fixed vacuum in the sealed glass tube.
Where it is desired to withdraw a pre-selected amount of blood, or to control the amount of vacuum that a vein is subjected to, plunger-operated syringes are employed. An example is found in U.S. Pat. No. 3,013,557 to Pallotta. The Pallotta syringe employs a barrel which is open at both ends, the forward end of which has means for mounting a venipuncture needle and the rearward end of it which is tapered into a conical configuration. A plunger is slidable within the barrel being attached to a plunger rod which is drawn away from the needle to draw a blood specimen. The plunger is tapered and upon entering the tapered conical portion of the barrel, becomes firmly wedged to seal the barrel. The needle is removed and the forward end of the syringe is capped. With the plunger firmly lodged in the barrel, the withdrawn plunger rod may be then broken off and the sealed barrel containing the blood specimen shipped to a laboratory for processing. While with the Pallotta syringe is capable of drawing a pre-determined quantity of blood, and controlling the amount of vacuum, once the plunger becomes lodged in the tapered portion of the barrel it cannot be removed without pressing it forward into the cylindrical portion of the barrel where the blood sample is present. Thereafter, it becomes very difficult, if not impossible, to reseal the syringe.
Subsequently, U.S. Pat. No. 3,577,980 to Cohen disclosed a multipurpose syringe having a slidable plunger which could be locked in its rearward position to create a vacuum in the syringe for the purpose of drawing blood. However, the rearward portion of the Cohen syringe was essentially closed making it impossible the remove the plunger for the purposes of removing a specimen of blood contained within the syringe cylinder.
Thereafter, U.S. Pat. No. 3,937,211 to Mertin disclosed a multipurpose syringe having a cylindrical barrel and a slidable plunger actuated by a frangible plunger rod. The rod passes through a cap which is screwed onto threads on the rearward end of the barrel. Also on the rearward end of the plunger are threads which are engagable with mating threads in a cylindrical portion of the cap. Since the cap includes both threads engagable with mating threads on the exterior of the barrel of the syringe and threads on the plunger, a problem exists in removing the specimen from the sealed barrel: unscrewing the cap from the barrel also unscrews the cap from the plunger. The plunger would then have to be removed by gripping the plunger rod. Should it then be desired to reseal the barrel, there's no way to assure that the cap would rethread itself into the plunger while simultaneously threading onto the barrel. The reason for this is that the plunger rod is frangible and is broken off after the cap is sealed.
With the above in view, it is an object of this invention to provide a multipurpose, plunger-actuated, recappable syringe for obtaining a blood sample and for storing and shipping it as well as for controlling the amount of vacuum, obviating all of the above problems.